PSO stands for “ProcessStandard Offset Printing”, a standard that was developed by Fogra and the German Printing and Media Industry together. The ProcessStandard Offset Printing is a set of standards for offset printing. With test equipment and control by measurments as described in the PSO, the printing process of the data delivery and data preparation on the platemaking is monitored, controlled and checked.
The following standards are summarized in PSO – “ProcessStandard Offset Printing:
ISO 00005-4: Optical density
ISO 02846-1: Printing inks
ISO 03664: Standard Lighting
ISO 12218: Platesetting analog
ISO 12641: Scanner Testchart
ISO 12642: Output test charts
ISO 12646: Monitors
ISO 12647-2: standard pressure
ISO 12647-7: Digital Proof
ISO 13655: Spectral color measurement
ISO 13656: Densitometric and colorimetric measurement
ISO 14981: Densitometer
A proof (correct: contract proof) is an ISO-certified testing device for the graphic arts industry. A proof simulates the colourfulness of offset or gravure printing in a colour and legally binding manner within the narrow tolerances of ISO 12647-7. Today, it is almost exclusively calculated using a RIP and then produced with inkjet printers on special proof papers.
The proof data is converted into separations, then reassembled into a composite image to correctly simulate overprinting and trapping. The data is then transferred as a newly created composite image to an inkjet printer, usually with more than 8 colours, which prints the data. In addition to the print data, a proof must also carry a UGRA/Fogra media wedge in order to be colour-consistent and legally binding. Thanks to the standardised wedge, the printer is able to check the proof for correctness. Since many printing companies do not have this measuring technique at hand, the proof is often provided directly with a test report that shows the correctness of the measured values of the media wedge directly on the proof.
Earlier methods such as Chromalin etc. are no longer available on the market today.
In addition to the term “proof”, terms such as colour proof or digital proof are also commonly used.
ISO 12647 defines the term “Validation Print” (ISO 12647-8) in addition to the highest standard of contract proof, “Proof” (ISO 12647-7). The Validation Print is characterized by the fact that although it is less accurate in colour, it can also be produced on laser printers. Compared to the contract proof, however, it accepts much higher colour deviations and is only legally binding after prior consultation. A real “proof”, i.e. a real contract proof according to ISO 12647-7 is currently not only by far the best variant in terms of colour, but also the only legally binding proof.
Further information: https://en.wikipedia.org/wiki/Prepress_proofing
In the ISO 12647 the ISO norm for standardized printing. It shows the main cornerstones for standardized, color-accurate prints.
The ISO 12647 is divided into 8 sections:
The authorities responsible for the proofing requirements are therefore in the standard ISO 12647-7. The year after the colon refers to the year of the current valid version of the standard. The ISO 12647-8 for the Validation Print was so last updated in 2012.